As for metabolic genodermatitis, indicators in metabolism show great importance: Zn deficiency is associated with the phenotype of perioral and perianal dermatitis, diarrhea highly suggests AE resulting from SLC39A4 mutations; organic acidemia reminds us to pay attention to MCD related to BT and HLCS variants; reduced prolidase enzyme activity and elevated levels of imidodipeptids hint us with PEPD-associated PD. Here, PEPD is linked to paroxysmal extreme pain disorder.